1. The Field of the Invention
The present invention relates to drilling equipment and to articulation assemblies for positioning a drill mast in particular.
2. The Relevant Technology
Drilling rigs are often used for drilling holes into various substrates. Such drill rigs include a drill head or drifter or both together as a double head system mounted to a mast assembly that is oriented at a desired drilling angle. The rig often includes mechanisms and devices that are capable of moving the drill head along at least a portion of the mast. The drill head often further includes mechanisms that receive and engage the upper end of a drill rod. The drill rod may be a single rod or a casing and rod combination as an overburden system or may be part of a drill string that includes a cutting bit or other device on the opposing end, which may be referred to as a bit end. In the case of a drill string, the drill string may include multiple rods, each of which has a length that is shorter than the usable length of the mast.
The drill head also applies one or more forces to the drill rod which is transmitted to the drill to string. If the applied force is a rotational force, the drill head may thereby cause the drill string rotate within the bore hole. The rotation of the drill string may include the corresponding rotation of the cutting bit, which in turn may result in a cutting action by the drill bit. The forces applied by the drill head can also include axial thrust forces, which may be transmitted to the drill string to facilitate penetration into the formation at the desired drilling angle.
Articulation assemblies are often provided on the drill rig to orient the drill mast at the desired angle. Such articulation assemblies often include a jib assembly that is configured to raise, lower, and tilt the mast assembly. In particular, jib assemblies often include a jib boom that supports the mast assembly. The jib boom is often raised and lowered by a lifting cylinder. A tilting cylinder is also often mounted directly to the jib boom on one end and coupled to the mast assembly on the other end. The tilting cylinder is extended and retracted in order to orient the mast assembly at a desired angle.
While such articulation assemblies are able to orient the mast assembly, the configuration of the articulation assemblies are often such that raising and lowering the mast assembly changes the drilling angle. Accordingly, in drilling operations where multiple holes are drilled at the same drilling angle, after one hole has been drilled the lifting cylinder is deployed to raise the mast assembly, the rig is moved to a new drilling location, the mast assembly is lowered, and the tilting cylinder is deployed to return the mast assembly to the appropriate drilling angle. Resetting the drilling angle each time can increase down time, thereby increasing the cost of the drilling operation.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.